Changes in Fair Value of Contingent Consideration Obligations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Contingent Consideration Obligations [Roll Forward]
Beginning balance	$ 90,009	$ 82,382
Contingent consideration liabilities recorded for business acquisitions	3,854	5,456	81,239
Payments	(39,117)	(3,100)
Loss (gain) included in earnings	2,504	1,643
Exchange rate effects	(1,597)	3,628
Ending balance	$ 55,653	$ 90,009	$ 82,382